(meteorobs) Meteor Activity Outlook for November 15-21, 2008

[Robert Lunsford]

As seen from the northern hemisphere, meteor rates continue to be strong in
November. While no major showers are active this month, the two Taurid
radiants plus the Leonids keep the skies active. The addition of strong
sporadic rates make November one of the better months to view meteor
activity from north of the equator. Skies are fairly quiet as seen from the
southern hemisphere this month. Activity from the three showers mentioned
above may be seen from south of the equator, but the sporadic rates are much
lower than those seen in the northern hemisphere.

During this period the moon reaches its last quarter phase on Wednesday
November 19th. At this time the moon will rise near midnight local standard
time (LST) and will remain in the sky the rest of the morning. At this time
successful meteor observations are possible if your sky is transparent and
you keep the bothersome moonlight out of your field of view. This weekend
the bright waning gibbous moon will severely hamper any attempts at
observing. The estimated total hourly rates for evening observers this week
is near five for those located in the mid-northern hemisphere (45 N) and two
for those viewing from the mid-southern hemisphere (45 S). For morning
observers the estimated total hourly rates should be near thirteen for those
located in the mid-northern hemisphere (45 N) and nine for those viewing
from the mid-southern hemisphere (45 S). Locations between these two
extremes would see activity between the listed figures. These rates assume
that you are watching from rural areas away from all sources of light
pollution. The actual rates will also depend on factors such as personal
light and motion perception, local weather conditions, alertness and
experience in watching meteor activity. Morning rates are reduced during
this period due to moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning November 15/16. These positions do not change greatly
day to day so the listed coordinates may be used during this entire period.
Most star atlases (available at science stores and planetariums) will
provide maps with grid lines of the celestial coordinates so that you may
find out exactly where these positions are located in the sky. A planisphere
or computer planetarium program is also useful in showing the sky at any
time of night on any date of the year. Activity from each radiant is best
seen when it is positioned highest in the sky, either due north or south
along the meridian, depending on your latitude. It must be remembered that
meteor activity is rarely seen at the radiant position. Rather they shoot
outwards from the radiant so it is best to center your field of view so that
the radiant lies at the edge and not the center. Viewing there will allow
you to easily trace the path of each meteor back to the radiant (if it is a
shower member) or in another direction if it is a sporadic. Meteor activity
is not seen from radiants that are located below the horizon. The positions
below are listed in a west to east manner in order of right ascension
(celestial longitude). The positions listed first are located further west
therefore are accessible earlier in the night while those listed further
down the list rise later in the night.

The following showers are expected to be active this week:

At this time of year debris from comet 2P/Encke produces a double radiant
very close to the position of the antihelion radiant. From now through the
end of November, it is impossible to resolve the antihelion meteors from
those produced by comet 2P/Encke. Therefore we suggest that observers simply
classify meteors from this area as either north or south Taurids.

The center of the large Northern Taurid (NTA) radiant is now centered at
04:08 (062) +23. This position lies in western Taurus some four degrees east
of the famous naked eye open star cluster known as the Pleiades or the Seven
Sisters. The center of the large Southern Taurid (STA) radiant lies at 04:04
(061) +16. This position also lies in western Taurus, eight degrees west of
the orange first magnitude star Aldebaran (Alpha Tauri). The two radiants
are separated by approximately seven degrees. Since they have the same right
ascension (celestial longitude), it is difficult to distinguish meteors that
move north or south out of the radiants. It is less difficult to distinguish
those meteors traveling east or west. These radiants are best placed near
the meridian at 0100 LST. At 29 and 27 km/sec., the average Taurid meteor
travels slowly through the skies.

Sirko Molau's new studies of video radiants has revealed that the Northern
Taurid's reach two plateaus of activity with the first occurring on October
20th. The moon subdued this activity so it was most likely not noticed. The
secondary peak is predicted to occur near November 13th and will be severely
hampered by a bright moon. The same study has revealed that the Southern
Taurids may have peaked near October 11 and that the activity for this
shower will remain fairly constant through the first week of November. After
that rates will dwindle until these meteors disappear near the end of
November.

The Leonids (LEO) are now producing bright meteors from a radiant located at
10:00 (150) +23. This position lies in western Leo, three degrees west of
the third magnitude star Zeta Leonis. Maximum activity is predicted to occur
on November 19 so current rates would most likely be near two per hour.
There are several predictions of short outbursts on the 17th and 18th so it
is advisable to view the Leonids during the entire period from the 17th
through the 19th despite the moonlight. Recent studies of video data by
Sirko Molau has indicated that the Leonids are active longer than expected,
with ZHR's of at least one through November 28. At 70km/sec., the average 
Leo
is swift with a high percentage of trains. The radiant is most favorably
located during the last dark hour before the onset of morning twilight.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately eight Sporadic meteors per hour during the last hour before
dawn as seen from rural observing sites. Evening rates would be near four
per hour. As seen from the mid-southern hemisphere (45S), morning rates
would be near three per hour as seen from rural observing sites and one per
hour during the evening hours. Locations between these two extremes would
see activity between the listed figures. Morning rates are reduced during
this period due to moonlight.

The list below presents a summary of the expected activity this week. Rates
and positions are exact for Saturday night/Sunday morning but may be used
all week.

Northern Taurids (NTA)  04:08 (062) +23  Velocity  29km/sec.
Hourly Rates: Northern Hemisphere - 2   Southern Hemisphere - 2

Northern Taurids (NTA)  04:08 (061) +16  Velocity  27km/sec.
Hourly Rates: Northern Hemisphere - 1   Southern Hemisphere - 1

Leonids (LEO) 10:00 (150) +23  Velocity  71km/sec.
Hourly Rates: Northern Hemisphere - 2   Southern Hemisphere - 2

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2008

Clear Skies!
Robert Lunsford
American Meteor Society